For example, a connecting portion of a rigid circuit board and that of a flexible circuit board are connected to a portable terminal, such as a portable telephone, in a casing. The connecting portions of these circuit boards are illustrated in FIG. 21.
Incidentally, a description will be given by designating the flexible circuit board and the rigid circuit board as a first circuit board 200 and a second circuit board 201, respectively.
A connecting portion 202 of the first circuit board 200 is such that a plurality of (i.e., five) first circuit patterns 204 are disposed in parallel to one another along a surface 203A of the flexible base material 203, and that first dummy terminals 205 are provided at both end portions 202A in an arrangement direction of each of the first circuit patterns 204, respectively.
A connecting portion 206 of the second circuit board 201 is such that a plurality of (i.e., five) second circuit patterns 208 are disposed in parallel to one another along a surface 207A of the flexible base material 207, and that second dummy terminals 209 are provided at both end portions 206A in an arrangement direction of each of the second circuit patterns 208, respectively.
Further, as illustrated in FIG. 22(A), the first connecting portion 202 and the second connecting portion 206 arranged to face each other via an adhesive agent 210, and are sandwiched by a pressurizing jig 211 and 212. The first circuit board 200 and the second circuit board 201 are heated and pressure-contacted to each other so as to be connected to each other.
At that time, as illustrated in FIG. 22(B), the adhesive agent 210 having been pushed out from between the first circuit pattern 204 and the second circuit pattern 208, which face each other, with the application of heat and pressure thereto adheres to the flexible base material 203 and the rigid base material 207. Consequently, the first circuit pattern 204 and the second circuit pattern 208 having been brought into surface contact with each other are fixed to each other.
Meanwhile, the contact of the upper mold 212 constituting the pressurizing jig 211 and 212 with a rear surface 203B causes the flexible base material 203 to apply heat of the upper mold 212 to the adhesive agent 210 provided on a front surface 203A. Consequently, the adhesive agent 210 is softened or liquefied.
At that time, the flexible base material 203 is softened. As illustrated in FIG. 12, the flexible base material 203 is elongated in the direction of an arrow along a surface thereof with the application of pressure thereto.
Then, as illustrated in FIG. 23, each of the first circuit patterns 204 made of the flexible base material 203 is dislocated with respect to an associated one of the second circuit patterns 208 made of the rigid base material 207. Thus, the design value of the conduction area of each of the first and second circuit patterns cannot be assured. Additionally, conduction might not be obtained in a case where the patterns are tremendously the dislocated.
Especially, in recent years, multilayered flexible base materials 203 and multilayered rigid base materials 207 have been being frequently used. Accordingly, it has been difficult to quickly transmit heat from the rear surface to the front surface of each of the flexible base materials 203 and the rigid base materials 207.
Thus, there is a tendency to set the surface temperature and the pressing force of the upper mold 212 to be higher than those of conventional one. Consequently, the problem of the elongation of the flexible base material 203 has been actualized.
For such a problem, a structure has been proposed, which is configured to adjust the intervals and the positions of the second circuit patterns 208 made of the rigid base material 207 to those of the elongated base material 203 by preliminarily predicting the elongation of the flexible base material 203 (see Patent Documents 1, 2, and 3).    Patent Document 1: JP-A-2002-32030    Patent Document 2: JP-A-2002-32031    Patent Document 3: JP-A-2002-341786